Practical Solutions for Large-scale CO2, H2O, and CH4 Emission Measurements

As cap-and-trade programs are implemented in regions around the world, consulting firms, land managers, and industrial consultants are seeking methods to measure greenhouse gas emissions and uptake at large scales. The eddy covariance method is often used to make large-scale emissions measurements. LI-COR (USA) manufactures complete eddy covariance sensor systems for measuring CO2, H2O, and CH4 emissions from many areas - including landfills, industrial sites, managed ecosystems, wetlands, urban areas, and more.

LI-COR provides CO2/H2O eddy covariance systems in both open-path and enclosed-path configurations. The LI-7500A Open Path CO2/H2O Analyser provides the lowest power requirements and can be operated with a solar power supply. The LI-7200 Enclosed CO2/H2O Analyser is best suited for areas with frequent rain or snowfall. It requires more power, but still can be operated by a solar power supply system. Both the LI-7500A and LI-7200 function as an eddy covariance system hub (with the included LI-7550 Analyser Interface Unit) and provide gas analyser control, sonic anemometer inputs, and data logging. For methane flux measurements, the LI-7700 Open Path CH4 Analyser is a drop-in addition to LI-COR eddy covariance systems.

To accommodate different site conditions, LI-COR offers 4 models of sonic anemometer, including omnidirectional and c-clamp styles. Anemometers that are purchased as part of an eddy covariance system include pre-wired cables that provide a simple and robust connection between the anemometer and gas analyser. For researchers who already have an anemometer, LI-COR offers pre-wired cables for Gill WindMaster, HS, and R3 models and the Campbell Scientific CSAT3, and a universal cable kit that can be customised for most other anemometer models.

Furthermore, LI-COR developed a biomet station that operates in tandem with the eddy covariance station. The biomet station can record data from nearly any additional sensor, provide system control for automated sensors, and can record data from well over 40 additional channels. Biomet data are recorded in the self-contained eddy covariance data files and in separate text files that can be evaluated independently of the eddy covariance data set.

To simplify eddy covariance data processing, LI-COR released free eddy covariance processing software called EddyPro. EddyPro reads the logged eddy covariance files directly and computes flux results from the data. It provides a computation mode called Express, which uses widely accepted algorithms to compute reliable flux results with ease. It also has a mode called Advanced, which provides state-of-the-art processing options for data sets that require alternative computation algorithms and in-depth analysis.

LI-COR offers a heavy-duty scientific instrument tripod that will support the eddy covariance system in high wind conditions. It is available with instrument mounting accessories to accommodate most station and sensor requirements. LI-COR also provide resources to help select suitable solar power supplies, remote system controllers, and telemetry components.